Conversion of hydrocarbon oils



y 1943 I c. H. ANGELL 2,319,201

CONVERSION OF HYDROCARBON OILS Filed llay 9, 1940 REACTI'ON OR TIMEFRACTIONATO CHAMBER EPARATING CHAMBER 27 26 I3 f .|4 u l2 com ENSER a:29 HEATER a. CATALYTIC CRACKING ZONE) 7 f if 9 UNVAPQRIZED I e 4 H AVY EINTER- I 9 l5 IQUID MEDIATE s- -J l0+ l6 l9 FRACTIONS mum I &ONCE USEDFRACTION E 4 la CATALYST 37 l coc a mc 2| as o CHARGE 2 I7 22 FRESHolLa. I 23 POWDERED CRACKING CATALYST 6 FRACTION-- 55 55: ATOR so so 57cognac 67 cu MBER com ENSER v s HEATER a 40 5| sl' 9 THERMAL CRACKING IZONE 43 .46 a E 1 42- "I f 52 58 saws 48*53' '}59 6| E a 44 HEAVY 62 luaum INTERMEDIATE FRACTIONS mum ,FRACTIONS v INVENTOR CHARLES H. ANGELLBY [Z ATTORNEY Patented May 18, 1943 CONVERSION OF HYDROCARBON OILSCharles H. Angeli, Chicago, Ill., assignor to Universal Oil ProductsCompany, Chicago, 11]., a

corporation of Delaware Application May 9, 1940, Serial No. 334,148

9 Claims. (cums-49) The invention relates to a combination catalytic andthermal cracking operation wherein the fresh charging oil for theprocess is admixed with relatively small amounts of a cracking catalyst,"in the form of a fine powder dispersed throughout the oil, and iscatalytically cracked while intermediate liquid conversion products ofthe catalytic cracking operation are thermally cracked and thencecommingled with catalystcontaining liquid residue derived from thecatalytic cracking step to effect appreciable further vaporization ofthe residue and catalytic cracking of. the residue and thermalconversion products, the vaporous products of the last mentionedcracking and residue-reducing operation being fractionatedv separatefrom the vaporous products of the first named catalytic crackingoperation to separately recover gasoline produced-by catalytic crackingof the charging oil and by subsequent cracking of the intermediateliquid conversion products and the residual oil.

The features and advantages of the invention and various alternativemodes of operating of the process provided will be explained inconjunction with the following description of the accompanyingdiagrammatic drawing which illustrates one specific form of apparatuswherein the improcess provided by the invention may be conducted.

Referring to the drawing, hydrocarbon oil charging stock for theprocess, which may be any oil amenable to catalytic cracking, issupplied, together with a relatively small percentage of finely divided,solid catalytic material, through line I and valve 2 to pump 3. Thesmall amount of'catalyst employed isdispersed substantially uniformlythroughout the oil and, with the small amount and relatively small sizecatalyst particles employed, the catalyst does not readily settle outduring heating. The stream of catalystcontaining charging oil issupplied from pump 3 through line 4 and valve 5 to heating coil 6disposed in a suitable furnace I.

' Although illustrated in a conventional manner in the drawing, theheater comprising coil 6 and furnace I may advantageously be one of thewell known vforms now in common use, wherein heat is transmitted at highrates to the fluid passing through that portion of the coil wherein itattains cracking-temperature, whereby the oil is quickly heated to therequired reaction temperature, and, preferably, the oil and dispersedcatalyst are then'passed through another portion of the coil, comprisinga soaking section, wherein heat is supplied thereto at a rate regulatedto maintain the reactants at or near the temperature previously attainedfor a predetermined time. In this particular instance, however, quickheating of the oil to the required reaction temperature, to minimizethermal cracking, is not so important as in other types of catalyticcracking operations wherein the oil is first heated to crackingtemperature in the absence of the catalyst and thereafter contacted withthe catalytic material. With the catalyst dispersed throughout the oilsupplied to the heating step, catalytic cracking of the oil will occuras soon as it reaches the required temperature for this reaction and,

since this temperature is usually below that re- I quired for activethermal cracking, the latter is inherently less pronounced than in othertypes of catalytic cracking operations. The method of operation hereinprovided also obviates the use of expensive heat exchanger type reactorsfor supplying theendothermic heat of reaction while the previouslyheated oil is in contactwith the catalyst and, on the other hand,obviates the practice, sometimes employed in other types of operations,of heating the oil alone to well above the temperature required for itscatalytic conversion and thereafter contacting the heated oil with thecatalyst, in order to'avoid the use of heat exchanger type reactors forthe contact plained, or alternatively, the heated products w from coil 6may, when desired, be directed through line l2 and valve I 3 intoreaction chamber M which, although not indicated in the drawing, ispreferably well insulated to conserve heat and wherein the catalyticcracking'reaction is allowed to continue at a somewhat reducedtemperature for a predetermined time. When reaction chamber I4 isemployed, the conversion products and catalyst supplied to'this zonefrom coil 6 are preferably directed downwardly therethrough andresulting conversion products and catalyst are directed from the lowerportion of the chamber through line l5 and valve l6 into line 9 whereinthey are cooled to below active cracking temperature and thence suppliedto chamber ll.

In the particular case here illustrated, cooling of the conversionproducts, prior to their introduction into chamber i I, is accomplishedas they pass through line 5 by directly commingling a suitable coolingoil therewith, this material being supplied to line 9 through line "andvalve la. The cooling oil employed may comprise, for example, regulatedquantities or selectedfractions of the intermediate liquid conversionproducts of either cracking step or regulated quantities of the lightdistillate product of the catalytic cracking step. Other means, not.illustrated, of accomplishing the desired cooling of the conversionproducts, such as, for example, a heat exchanger interposed in line 9,wherein useful heat is hecovered from the conversion products by passingthe same in indirect heat exchange relation with any desired coolingmedium, may be employed within the scope of the invention.

In chamber ll relatively clean vaporous products of the catalyticcracking operation are separated from a liquid residue which compriseshigh-boiling fractions of the conversion products and includessubstantially all of the finely divided catalyst particles. The catalystcontaining residual liquid is directed from the lower portion of chamberll through line l9 and valve 20 to pump 2| and is supplied therefromthrough line 22 and valve 23 into the coking zone, which will be laterdescribed.

The relatively clean vaporous products of the.

catalytic cracking operation are directed from the upper portion ofchamber H through line 24 and valve 25 to fractionator 26 wherein theircomponents boiling within the range of the desired final lightdistillate product of the catalytic cracking step are separated fromtheir higher boiling components by condensing the latter as refluxcondensate.

Fractionated vapors of the desired end-boiling point are removed,together with normally gaseous products of the catalytic crackingoperation, from the upper portion 01' fractionator 26 and directedthrough line 21 and valve 26 to condenser 29 wherefrom the resultingdistillate and uncondensed gases pass through line 30 and valve 3| tocollection and separation in receiver 32. Distillate collected inreceiver 32 is directed therefrom through line 33 and valve 34 tostorage or elsewhere, as desired. Uncondensed gases areremoved from thereceiver through line 35 and valve 36 to storage or elsewhere, asdesired,

this material preferably being supplied to conventional absorptionequipment, not illustrated, wherein desired high-boilin components ofthe normally gaseous products and/or uncondensed normally liquidfractions are recovered therefrom. When desired, regulated quantities ofthe distillate collected in receiver 32 may be returned by well knownmeans, not illustrated, 'to

the upper portion of fractionator 26 to serve as a cooling and refluxingmedium in thi zone.

Intermediate liquid conversion products of the catalytic cracking step,comprising all or selected fractions of the reflux condensate formed infractionator 26, are directed therefrom through line 31 and valve 38 topump 39 wherefrom they are supplied through line 40 and valve 4| tothermal cracking treatment in heating coil 42.

Heating coil 42 is disposed in a furnace 43 of any suitable conventionalform and the oil passing through the coil is heated to the desiredthermal cracking temperature, preferably at a substantialsuperatmospheric pressure. The resulting. highly heated products aredirected, in the case here illustrated, from coil 42 through line 44 andvalve 45 into the coking zone. It is also within the scope of theinvention to employ a. reaction chamber succeeding heating coil since itis employed to advantage 42, wherein further cracking of all or aportion of the heated products from coil 42 is accomplished prior totheir introduction into the coking zone. This reaction chamber, notillustrated, may be of the same general type as chamber l4 and may beconnected'with line 44 in the same manner as chamber I 4 is connectedwith lines 8 and 9.

Although a single coking chamber may be employed, when desired, thecoking zone preferably comprises a plurality of chambers (two beingillustrated in the drawing) which are alternately operated and cleanedand prepared for further operation in order that the coking step, incommon with the rest of the system, may be operated continuously. Thecatalyst-containing residue from chamber II is contacted with theproducts of the thermal cracking operation from coil 42 either within orprior to their introduction into the coking zone. To accomplish this, inthe particular case here illustrated, a line 46 is provided whichconnects lines 44 and 22 and from which branch lines 41, 41', 49 and49', containing the respective valves 48, 48', 56 and 50, communicatewith coking chambers. Lines 47 and 49 lead to coking chamber 5| andlines 4'! and 49' lead to coking chamber 5i. Thus, the mixture ofcatalyst-containing residue and thermal conversion products may beselectively supplied to either the upper, or lower portion of either ofthe coking chambers or the hot thermal conversion products may besupplied to the lower portion of either of the coking chambers while thecatalyst-containing residue from chamber II is supplied to the upperportion of the same chamber. In any case, the catalyst-containingresidue is contacted with the hot thermal conversion products, therebyappreciably further vaporized and the heavy non-vaporous compoing oil,considerable catalytic cracking will accompany the coking operation, thecatalyst-containing residue commingling with the hotter thermalconversion products to heat the residual oil to a temperature at whichthe desired further vaporization and further cracking will occur, whilethe thermal conversion products are also subjected to the action of thecatalyst.

The problems encountered in recovering and,

reactivating the relatively small quantities of finely divided catalystemployed in a catalytic cracking operation of the general type describedordinarily makes this procedure too expensive to be justifled on aneconomic basis. However, the presence of catalyst in the residual oil isdetrimental to the use of the latter as fuel oil and must be settled orfiltered therefrom. Recycling of the catalyst-containing residue to thecatalytic cracking coil, in order to obtain the benefit of any remainingactivity in the catalyst, is not a particularly successful expedient,since coking diflicul-' ties will ordinarily be encountered in theheating coil and subsequent equipment. In the present invention theseproblems are obviated without sacrificing the remaining activity of thecatalyst in the coking step and after being thus utilized is largelyincluded with the resulting coke. Its presence in the latter isadvantageous in that it will increase spective valves 53 and 53'. v beemployed, when desired, as a means of introthe ash content which isordinarily negligible in petroleum cokes. The ash content imparted tothe coke by the catalyst makes it a moreconvenient fuel to use and willmaterially assist in preventing burned out grates or, when employed astem, cleaned and prepared for further operation,

while coking continues in another chamber.

Chambers and 5| are provided with drain lines 52 and 52, respectively,containing the re- These lines may also ducing steam, water or othersuitable cooling medium into the chamber, after it has been isolatedfrom the rest of the system, in order to hasten cooling and facilitateremoval of the coke, which maybe accomplished in any well known manner.

Vaporous products of the coking and catalytic cracking and cokingoperations which take place in chambers 5| and 5|, are directedtherefrom through the respective lines 54 and 54', controlledrespectively by valves 55 and 55', and are supplied .through line 56 tofractionator 51. 'Ordinarily, the vapors supplied to fractionator 51will include some small quantity ofrelatively heavv liquid particles,such as tar and the like, carried over from the coking zone and,preferably, these materials areseparated in the lower portion of column51 from relatively clean vapors which include substantial quantities ofmaterial boiling within the range of gasoline and heavier liquidconversion products, the latter being, condensed in fractionator 51 asreflux condensate.

The heavier liquid fractions are removed fronr line 64 and valve 55 or,preferably, is returnedy through valve 66 in line 63 to further crackingtreatment in heating coil 42. Any other desired treatment of all or aportion of the total reflux condensate formed in fractionator 51 orselected fractions thereof is entirely within the scope of theinvention. For example, this material may be passed through a separatethermal cracking coil, not illustrated, whereupon resulting products aresupplied to the coking zoneor it may, when desired, be returned toheating coil 6 by well known means, not illustrated, for catalyticcracking treatment incommingled state with the charging oil or it may besupplied, after mixing cracking catalyst therewith, to a separatecatalytic cracking coil, not shown, wherefrom resulting products aredirected to reaction chamber M or to separating chamber coking steps,from. the upper portion of fractionator 51 and directed through line 61and valve 68 to condenser 59 wherefrom the resulting distil-Fractionated vapors of the desired end-boiling point are removed,together with normally gaseous products of the last described crackingand late anduncondensed gases are directed through line 10 and valve 1|to collection and separation in receiver 12. The distillat cpl l ectedin receiver 12, which ordinarily comfl ii's" gasoline of differentcharacteristics from th t recovered in receiver 32, is directed fromrece ver 12 through line 13 and valve 14 to storage or elsewhere, asdesired. The uncondensed gases, are removed from. receiver 12 throughline 15 and valve 16 to storage, suitable absorption equipment, notillustrated, or elsewhere, as desired. When desired regulated quantitiesof the distillate collected in receiver 12 may be recycled, by wellknown means not shown, to the upper portion of fractionator 51 to serveas a cooling and refluxing medium in this zone. I

Any solid material in finely divided state which will function to effectcatalytic'cracking of the charging oil, when employed in the mannerdescribed and relatively in small quantities, may be employed as thecracking catalyst within the scope of the invention. One such materialwhich I have found particularly suitable comprises a substantiallyimpalpable powder consisting essentially of silica and selected metaloxides such as, for example, alumina, thoria, zirconia and titania,alone or in combination. The silica may be precipitated from a sodiumsilicate solution by acidification and the resulting precipitated fineparticles of silica impregnated with the desired metal oxide or oxidesderived from the salts of the metal or metals, or the catalyst powder,including the silica and one or more of the metal oxides may be preparedby co-precipitation. No novelty is claimed herein for the particularmethod of preparing the catalyst powder.

The invention also contemplates the use of certain natural metalsilicates in finely ground or pulverized form, such materials being moresuitable for one embodiment of the catalytic cracking operationcontemplated by the invention than they are for operations in which thecracking catalyst must be reactivated .to make the process economical,since other materials 'will depend upon the composition and the size ofthe catalyst particles,'as Well as the nature of the v charging oil, andthe temperature and pressure conditions utilized. It may range, forexample, from 10 to 0.10% by weight of the charging oil. Otherconditions being the same, the amount of catalyst required is decreasedwith a reduction in the particle size of the catalyst. For example, aslittle as 0.25% of synthetic silicaalumina catalyst prepared as asubstantially impalpable powder by precipitation has been successfullyemployed in cracking paraflinic distillates and even less may quiteprobably be employed under some conditions.

The operating conditions employed in conducting the process will vary,depending upon the type of charging oil utilized and the nature of thecatalyst employed. In cracking predominantly paratfinic distillates,such as Pennsylvania gas-oil, for example, with a synthetically prepared silica-alumina catalyst powder, such as above mentioned,temperatures of the order of 850 to 1000 F. are preferably employed inthe inital catalytic cracking step with superatmospheric pressures ofthe order of 30 to 150 pounds, or thereabouts, per square inch. Thereaction chamber, when utiilzed, is preferably operated at substantiallythe same pressure as that employed at the outlet of heating coil 6 and,when pressures above 50 pounds, or thereabouts, per

square inch are utilized in the initial catalytic cracking zone, thesucceeding separating chamber may, when desired, be operated at asomewhat reduced pressure which preferably is substantially equalized inthe succeeding fractionating condensing and collecting equipment. Thethermal cracking zone to which intermediate liquid conversion productsof the initial catalytic cracking step are supplied preferably utilizestemperatures of the order of 900 to 1000 F., or thereabouts, preferablywith a superatmospheric pressure, measured at the outlet of heating coil42, of the order of 150 to 500 pounds or more per square inch. Thecoking zone is preferably operated at a superatmospheric pressure of theorder .of 30 to 150 pounds, or thereabouts, per square inch. Thetemperature employed in the coking zone will, of course, depend-upon thetemperatures and relative quantities of the catalyst-containing residueand thermal conversion products supplied thereto and will ordinarily beof the order of 800 to 900 F., or thereabouts. Preferably, the pressureemployed in the coking'zone is substantially equalized in the succeedingfractionating, condensing and collecting equipment.

As an example of onespecific operation of the process, as it may beconducted in an apparatus such as illustrated and above described, thecharging stock is a Pennsylvania gas-oil of approximately 36 A. P. I.gravity to which approximately 0.5% of synthetically preparedaluminasilica powder is added. and substantially unlformly dispersedthroughout the oil. The catalyst-containing charge is quickly heated incoil 6 to a temperature of approximately 950 F. and the resultingproducts, after passing through reaction chamber I 4, are cooled to atemperature of approximately 760 F. and introduced into separatingchamber II. A superatmospherlc pressure of approximately 100 pounds persquare inch is employed at the outlet of heating coil 6 and at theoutlet of chamber l4. The pressure employed in chamber l l isapproximately 50 pounds per square inch. Cooling of the conversion products, prior to their introduction into chamber I l, is accomplished, inpart, by the pressure reduction and, in part, by cooling and thencecommingling regulated quantities of the intermediate liquid conversionproducts from fractionator 26 therewith. Fractionator 26, condenser 29and receiver 32 are operated at substantially the same pressure as thatemployed in the separating chamber.

The total intermediate liquid conversion products from fractionator 2Bare thermally cracked in heating coil 42, the maximum temperature inthis zone being approximately 960 F. and the pressure employed at theoutlet therefrom being approximately 350 pounds per square inch,superatmospheric.

The coking zone to which catalyst-containlng residue from chamber H andhot thermal conversion products from coil 42 are supplied is operated ata superatmospheric pressure of approximately 80 pounds per square inch,this pressure being substantially equalized in the succeedingfractionating, condensing and collecting equipment. A small quantity ofheavy liquid conversion products is removed from the lower portion offractionating column 51 and the relatively clean intermediate liquidproducts formed as reflux condensate in this zone are returned to coil42 for further cracking treatment.

In an operation such as above described, one may expect to obtainapproximately 26% of catalytically cracked gasoline having an octanenumber of approximately 7-8 as determined by the motor method orapproximately 89 as determined by the research method. The gasolineproduced in the thermal cracking, coking and secondary catalyticcracking steps of the system may amount to approximately 36% based onthe charging oil and have an octane number of approximately 70 asdetermined by the motor method. Additional products ofthe processconsist predominantly of low volatile coke, which has an ash contentmaking it suitable for domestic or stoker fuel, normally gaseousfractions, containing over 40% of readily polymerizable olefins, and arelatively small amount of heavy liquid products which latter arerecovered as bottoms from fractionator 57.

I claim as my invention:

1. A hydrocarbon oil cracking process which comprises, cracking an oilsusceptible to catalytic cracking in the presence of a cracking-catalystpowder, separating from the resulting conversion products relativelyclean vapors and lyst-containing residue, fractionating said vapors torecover good antiknock gasoline therefrom and to condense higher boilingcomponents thereof as reflux condensate, thermally cracking refluxcondensate resulting from said fractionation to form additional yieldsof good antiknock gasoline, commingling resultant heated products withsaid catalyst-containing residue and reducing the mixture to arelatively dry mass, containing catalyst powder.

2. A hydrocarbon oil cracking process which comprises, cracking an oilsusceptible to catalytic cracking in the presence of a cracking-catalystpowder under catalytic cracking conditions of temperature and pressure,separating from the resulting conversion products relatively cleanvapors and a catalyst-containing residue, fractionating said vapors torecover good antiknock'gasoline therefrom and to condense higher boilingcomponents thereof as reflux condensate, thermally cracking refluxcondensate resulting from said fractionation in a zone separate fromthat wherein said catalytic cracking of the first named oil isaccomplished to form additional yields of good antiknock gasoline,commingling resultant heated products with said catalyst-containingresidue and reducing the mixture to a relatively dry mass, containingcatalyst powder, in a zone separate from that; wherein thecatalyst-containing residue is separated from the aforementioned vapors.

3. A hydrocarbon oil cracking process which comprises, cracking an oilsusceptible to catalytic a catathermally cracking reflux condensateresulting from said fractionation in avzone separate from that whereinsaid catalytic cracking of the first named oil is accomplished to formadditional yields of good antiknock gasoline, commingling resultantinated products with said catalyst-containing residue and reducing themixture to a relatively dry mass, containing catalyst powder.

4. A hydrocarbon oil cracking process which comprises, cracking an oilsusceptible to catalytic cracking in the presence of a catalyst capableof promoting the cracking reaction and under conditions at which it isconverted to form good antiknock gasoline, said catalyst bein dispersedin the form of a powder throughout a flowing stream of the oilundergoing said heating, separating from the resulting conversionproducts vapors containing good antiknock gasoline and higher boilingfractions, and a catalyst-containing residue, fractionating the vaporsto recover said good antiknock gasoline therefrom and to condense higherboiling components thereof as reflux condensate, thermally crackingreflux con densate resulting from said fractionation in a zone separatefrom that wherein the first named oil is catalytically cracked, andcommingling hot conversion products of the thermal cracking step withsaid catalyst-containing residue to reduce the latter to a substantiallydry mass, containing catalyst powder, in a zone separate from thatwherein the catalyst-containing residue is separated from theaforementioned vapors.

5. A hydrocarbon oil cracking process which comprises, cracking an oilsusceptible to catalytic cracking, in the presence of a catalyst capableof promoting the cracking reaction and under conditions at which it isconverted to form good antiknock gasoline, said catalyst being dispersedin the form of a powder throughout a flowin stream of the oil undergoingsaid heating, separati-ng from the resulting conversion products vapors,containing said good antiknock gasoline and higher boiling fractions,and a catalyst-containing residue, fractionating the vapors to recoversaid good antiknock gasoline therefrom and to condense higher boilingcomponents thereof as reflux condensate, thermally cracking refluxcondensate resulting from said fractionation in a zone separate fromthat wherein the first named oil is catalytically cracked,- co fnglinghot conversion products of the thermal cracking step with saidcatalyst-containing residue to reduce the latter to a substantially drymass, containing catalyst powder, in a zone separate from that whereinthe catalyst-containing residue is separated from the aforementionedvapors and fractionating vaporous products. of the thermal crackingoperation and vaporous products of said reducing operation separate fromthe vaporous products of said catalytic cracking operation to separatelyrecover therefrom additional yields of good antiknock gasoline.

6. A hydrocarbon oil cracking process which comprises, cracking an oilsusceptible to catalytic cracking, in the presence of a catalyst capableof promoting the cracking reaction and under con-' vapors, containingsaid good antiknock gasoline and higher boiling fractions, and acatalyst-containing residue, fractionating the vapors to recover saidgood antiknock gasoline therefrom and to condense higher boilingcomponents thereof as reflux condensate, thermally cracking reflux con-I catalyst powder, in a zone separate from that wherein thecatalyst-containing residue is separated from the aforementioned vapors,fractionating vapors resulting from the thermal cracking and reducingsteps to recover additional good antiknock gasoline therefrom and tocondense higher boiling components thereof as reflux condensate andreturning reflux condensate resulting from the fractionation of saidvaporous products of the thermal cracking and reducing steps to thethermal cracking step.

7. A hydrocarbon oil conversion process which comprises, heating aflowing stream of oil susceptible to catalytic cracking'to a temperatureat which it is catalytically converted to form good antiknock gasoline,accomplishing said heating and catalytic cracking of the oil in thepresence of a. finely divided active cracking catalyst dispersedthroughout the stream of oil undergoing treatment, cooling a stream ofthe resulting conversion I products, including said catalyst, to atemperature at which detrimental further cracking thereof is prevented,separating from the resulting cooled conversion products vapors, which.

comprise said good anti-knock gasoline and higher boiling components,and a residual liquid containing substantially all of the catalystparticles, supplying a catalyst-containing residual oil from the zone ofsaid separation to a coking zone, fractionating said vapors to recoversaid good antiknock gasoline therefrom and to condense higher boilingcomponents thereof as reflux condensate, heating reflux condensateresulting from said fractionation to a thermal cracking temperature in azone separate from that wherein the first named oil. is catalyticallycracked, introducing resulting highly heated products into the cokingzone, therein effecting further catalytic cracking and reduction of theresidual oil to an ash-containing coke,-removing resulting vaporousproducts from the coking zone and separately fractionating the same torecover therefrom additional yields of good antiknock gasoline.

8. A hydrocarbon oil conversion process which comprises, heating aflowing stream of oil susceptible to catalytic cracking to a temperatureat which it is catalytically converted to form good antiknock gasoline,accomplishing said heating and catalytic cracking of the oil in thepresence of a flnely divided active cracking catalyst dispersedthroughout the stream of oil undergoing treatment, cooling a stream ofthe resulting conversion products, including said catalyst, to atemperatureat which detrimental further cracking thereofis prevented,separating from the resulting cooled conversion products vapors whichcomprise said good antiknock gasoline and higher boiling components anda residual liquid containing substantially all of the cata- Jectinghydrocarbon oil to catalytic cracking con- 15 ditions in admixturevwitha powdered cracking catalyst, separating the resultant products intovapors and a residual liquid containing the powdered catalyst,fractionating the vapors tocondense heavier fractions thereof, thermallycracking resultant reflux condensate contacting heated products thusformed with said catalyst-containing residual liquid in a vaporizingzone toreffect further vaporization of the residual liquid by the heatof said products, and maintaining said vaporizing zone under catalyticconversion conditions to effect further conversion therein with the aidof said catalyst.

CHARLES H. ANGELL.

